Drafting instrument



J. D. CARDINELI.

DRAFTING INSTRUMENT Filed Apri). 28, 1.948

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Patented May 30, 1950 UNITED STATES PATENT OFFICE DRAFTING INSTRUMENT John D. Cardinell, Montclair, N. J.

Application April 28, 1948, Serial No. 23,812

2 Claims. 1

By way of explanation it might be stated that drafting instruments, particularly long rulers used by draftsmen, eventually become warped and twisted to such a degree that the instrument must be discarded.

It is, therefore, the primary object of the invention to provide means of a rigid character for attachment to the usual drafting instrument which will hold the drafting instrument against warping and twisting.

Another object of the invention is to provide an improved drafting instrument comprising a straight edge ruler having parallel opposed edges and a metal cover plate with transversely extending longitudinally spaced combined reinforcing and cover plate securing strips.

A further object of the invention is to provide an improved straight edge drafting instrument which will be highly efficient in use, and relatively inexpensive to manufacture and produce.

Other objects will appear as the description proceeds.

In the accompanying drawings which form a part of this application:

Figure 1 is a vertical longitudinal sectional view through the improved drafting instrument.

Fig. 2 is a sectional view taken on the line 2-2 of Fig. 1.

Fig. 3 is a sectional view taken on the line 3-3 f Fig 1.

Fig. 4 is a perspective view of the improved drafting instrument showing one end thereof in sectional elevation.

Like characters of reference are used throughout the following specification and the accompanying drawing to designate corresponding parts.

In carrying out the invention, there is provided an improved drafting instrument comprising a straight edge ruler generally designated by the reference numeral I, the same having a longitudinally extending body strip 2 with plastic outwardly sloping or tapering ruling edges 3 and 4, suitably secured to the opposite edges of said body strips 2.

A longitudinally extending light metal reinforcing cover 5 is formed with a, convex upper surface, with concave gripping edges 6 and l, and with inwardly directed supporting terminal fianges 8 and 9.

A plurality of transversely extending longitudinally extending cover securing and clamping strips I0 are provided, and are substantially U- shaped in cross section with threaded vertical bores I I formed through the opposite ends of said strips I0 for receiving the screw bolts I2 formed with countersunk heads I3, said bolts extending through the body 2 of the instrument I. The strips I0 are further provided with the laterally extending clamping ears I4 and I5, which are adapted to rest upon the flanges 8 and 9 of the cover 5 to firmly lock the same in position when said bolts I2 are screwed tight.

From the foregoing description, it will be ap parent that there has been described a highly efficient form of straight edge drafting implement.

While the preferred embodiment of the instant invention has been illustrated and described, it will be understood that it is not intended to limit the scope of the invention thereto, as many minor changes in detail of construction may be resorted to without departure from the spirit of the invention.

Having thus described my invention what l claim as new and desire to secure by Letters Patent of the United States is:

1. In a drafting instrument, a straight edged rule, transversely disposed clamping strips having threaded openings, positioned on the rule, a cover of substantially U-shape in cross section, having inwardly extended parallel marginal anges fitted under the ends of the clamping strips, the side edges of the cover being spaced from the edges of the rule, screws extending through the rule and being tted into threaded openings of the clamping strips drawing the clamping strips into close engagement with the flanges securing the cover to the rule, and the sides of said cover being concave providing gripping surfaces for the hand of the person using the rule.

2. In a drafting instrument, a straight edged rule, transversely disposed clamping strips having threaded openings intermediate their ends, secured to the rule, laterally extended clamping ears formed on the ends of the clamping strips, a cover of substantially U-shape in cross section. having inwardly extended parallel marginal flanges fitted under the clamping ears of the clamping strips, screws extending through the rule and through the threaded openings of the clamping strips drawing the clamping strips into close engagement with the rule and cover, and said cover having longitudinally disposed grooves formed in the sides thereof providing gripping surfaces for the fingers of the person handling the rule.

JOHN D. CARDINELL.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 422,701 Benzinger Mar. 4, 1890 903,079 Goddard Nov. 3, 1908 2,027,619 Rutherford Jan. 14, 1936 2,102,008 Klitsche Dec. 14, 1937 2,220,826 Place Nov. 5, 1940 

